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Acute Exposure to Circularly Polarized 50-Hz Magnetic Fields of 200–300 µT Does Not Affect the Pattern of Melatonin Secretion in Young Men

Centre for Chronobiology, School of Biomedical and Life Sciences, University of Surrey, Guildford, Surrey GU27XH, United Kingdom

Address all correspondence and requests for reprints to: Dr. Guy Warman, Department of Anaesthesiology, Faculty of Medical Health Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand. E-mail: g.warman{at}auckland.ac.nz.

Environmental exposure to time-varying (alternating current) magnetic fields (MFs) produced by electrical current flow is a perceived public health risk. Several epidemiological studies report correlations between MF exposure and carcinogenesis. It has been hypothesized that MF-induced suppression of melatonin could provide the mechanism by which this effect is mediated. Here, we describe results from a controlled laboratory-based study designed to detect changes in human melatonin secretion after a 2-h exposure to 200–300 microTesla, 50 Hz circularly polarized MF. Exposure was timed to occur before or during the nightly melatonin rise, and levels administered were some 4–6 times higher than the commonly encountered maximum levels. Results from 19 male subjects aged between 18 and 35 yr indicate that acute exposure to 50 Hz MFs of this nature does not result in significant suppression, alteration of peak levels, or a change in timing of the nighttime melatonin rise. We conclude that acute exposure to 50 Hz MFs does not have a significant effect on the normal nighttime production of melatonin in young men.

This work was supported by the National Grid Co. and a Biotechnology and Biological Research Council Cooperative Awards in Science and Engineering Ph.D. studentship (to H.T.).

Current address for G.W.: Department of Anaesthesiology, University of Auckland, Private Bag 92019, Auckland, New Zealand.

Abbreviations: AC, Alternating current; CT, circadian time; MF, magnetic field; Mid X, midpoint between baseline and melatonin peak.

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